1. Field of the Invention
The present invention relates to a ceiling fan, and more particularly to a ceiling fan that uses an outer-rotor type direct current brushless motor as a driving source.
2. Description of Related Art
DC motors are widely mounted in ceiling fans as driving sources to drive blades. The DC motor comprises a rotor with a permanent magnet, a stator with multiple coils, brushes and a commutator. As the rotor rotates, the brushes contact the commutator to conduct external DC power to the coils of the stator. The coils accordingly produce a magnetic field that repels the permanent magnet to drive the rotor to rotate in a particular direction.
With the high frequent contact and separation, the surfaces of both the brushes and the commutator easily have abrasion to cause sparks when the brushes separate from the commutator. The sparks may further affect other electronic components in the motor, i.e. the electromagnetic interference problem. Therefore, for the ceiling fans using the foregoing DC motor as the driving source, the possibility of malfunction is reasonable high.
Therefore, the present invention provides a new ceiling fan with an outer-rotor type DC brushless motor to overcome the forgoing mentioned drawbacks.